System of equalizing the lifting speed of differently loaded hydraulic jacks



Dec. 28, 1937. c, HENRY 2,103,530

SYSTEM OF EQUALIZING THE LIFTING SPEED OF DIFFDRENTLY LOADED HYDRAULICJAGKS Filed Sept. 5, 1935 4 Sheets-Sheet l K m N N -Invenior CarIeLHenryDec. 28, 1937. D, HENRY" 2,103,530

SYSTEM OF EQUALIZING THE LIFTING SPEED OF DIFFERENTLY LOADED HYDRAULICJACKS Filed Sept. 5, 1935 4 Sheets-Sheet 2 I I! I I.

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SYSTEM OF EQUALIZING THE LIFTING SPEED OF DIFFERENTLY LOADED HYDRAULICJACKS Filed Sept. 5, 1935 4 Sheets-Sheet 3 Sepauaio uni-lei filo-Z 7?:com mon I reserve tank 4/0.! "0.2 Dalila wee was I autlef' P I I l i a lI II VI 1 .Zeparnie I I I I ("cannon or I l 9 I I fepamfie l'uiake I Dcvan/for OarIeD. Henly Dec. 28, 1937. c HENRY 2,103,530

SYSTEM OF EQUALIZING THE LIFTING SPEED OF DIFFERENTLY LOADED HYDRAULICJACKS Filed Sept. 5, 1935 4 Sheets-Sheet 4 Omelet/$6.1 Outlet 4 0. 2

Inventor t'az'lenflenzy Patented Dec. 28, 1937 UNITED STATES amuseSYSTEM OF EQUALIZING SPEED OF DIFFERENTLY DRAULIC JACKS THE IJFTINGLOADED HY- Carle D. Henry, South Portland, Maine, assignor to MaineSteel, Inc., corporation of Maine South Portland, Maine, a

Application September 5, 1935, Serial No. 39,214

11 Claims.

This invention relates to material handling equipment intendedespecially for use on track laying or crawler tractors and has for itsgeneral object to provide a means of attaining an equalized liftingspeed in two or more separate hydraulic jacks carrying different loadsat the same time when only a single source of power is available tooperate the pumping mechanism.

The crawler tractor is so designed that each of its two tracks may moveup and down or oscillate independently of each other except at one pointwhich is usually at or near the center of the rear drive sprocket. Thetwo tracks tend to pivot around this common point and because this isthe only point along the track frames where one track remainspermanently in the same relationship to the other track it is the pointfrom which accessory material handling equipment is ordinarily pushed.

Accepting this point as the conventional push point, the problem is tolift or adjust the accessory'equipment in a vertical plane while it isbeing pushed by and ahead of the trator.

The point or points from which the lifting power is applied mustobviously be ahead of the pivot and push point previously referred toand because it is ahead of this point it is equally obvious that thelifting is done from points which do not stay in the same relativepositions with each other and that therefore a single lift isimpractical and there must be a separate lift or hydraulic jack on eachside of the tractor.

Both lifting jacks are commonly operated by means of hydraulic pressuregenerated by a pump connected with the power take-off of the tractor.The dlfllculty with the conventional type of lift is that when one sideof the equipment to be lifted is loaded with snow or dirt and the otherside is not so loaded, any attempt to operate the two jack lifts resultsin lifting the light side to the limit of its stroke before the loadedside starts up, because in accordance with the well known principle ofhydraulics, oil pressure originating from a single source, with twopossible outlets, will flow through the outlet having the least loaduntil the resistance in that outlet is built up to equal the pressurenecessary to lift the load on the other outlet.

Hence when the operator of a bulldozer, or a trail-builder, or a snowplow, or a snow plow wing, opens his lifting valve, first one end of theequipment comes up and then the other end, and only an analysis of theload which happens to be on the equipment at that particular minute willfore-warn the operator as to which end will lift first, or how far itwill lift before the other end starts after it.

To eliminate this uncertainty and to secure an equal lifting speed oneach side regardless of different loading my invention includes ahydraulic pump which may be of gear, plunger, or other hydraulic typeand which is of multiple construction so that two or more separatestreams of oil are pumpedto the diilierent jacks.

With such multiple-stream pump may be included a valve assembly by whichthe oil or other fluid under pressure from all of the multiple pumpingunits may be combined as'a single stream to a single jack thereby toobtain the maximum lifting speed and additional valve adjustmentsenabling the several Jacks to be lifted simultaneously with a uniformflow of oil to each regardless of variation in their respective loads.

By means of my multiple pump and valve assembly the blade of atrail-builder, for, example, can be tipped up and set at an angle withthe maximum speed by combining all the oil flow to the jack on one end,and thereafter by using the valve assembly to separate the flow to thejacks on either side, it can be lifted and lowered as a whole and stillretain the tipped position arrived at by using the combined flow to thesingle jack.

Or considering a snow plow wing with a Jack on either end where the loadon one end is much heavier than the load on the other end, such wingmay'be lifted in a level position with the divided flow, or speedilytilted to any angle by the combined flow, and such angle having beenonce attained, the wing can be lifted as a whole by the divided flow andwhile being lifted can maintain its tilt even when one end is loaded tocapacity and the other end is light.

The same principle can be used to adjust the angle of a trail-builderblade in a horizontal plane, and in fact is generally applicable to usein connection with all equipment mounted on tractors or other types ofmotive equipment which needs to be quickly and positively adjustedduring its use and operation.

In the accompanying drawings I show an embodiment of my invention whichhas been i'ound highly satisfactory under actual service conditions. Inthe drawings:-

Flg. 1 is a side elevation of a conventional tractor equipped with meansfor equalizing the lifting speed of the hydraulic jacks commonlyemployed for raising the material-handling implement, here shown as themoldboard o! a bulldozer, trail-builder, or the like.

Fig. 2 is a section on the line 2-2 of Fig. 3 through a multiple gearpump such as contemplated by my present invention.

Fig. 3 is a fragmentary plan section of such pump.

Fig. 4 is a diagrammatic view of the hydraulic system as used in myinvention but showing pumps of the plunger type rather than the multiplegear type as shown in Figs. 2 and 3, and

5 is a. diagrammatic view of a variation of the hook up wherein two gearpumps are placed side by side and driven from a common shaft.

Referring to Fig. l I have indicated at In the moldboard of a bulldozeror trail-builder. -For this however can be substituted a snow plow orany other implement of the material handling type requiring upward ordownward or angular adjustment and which is made for use with a tractoror other type of motive equipment.

I have indicated at H the tracks of a tractor l2 of conventional type,and at It the push members which push the moldboard, plow or otherequipment mounted on the tractor. The push members 13 are pivoted at ornear the center of the rear drive sprocket II.

I have indicated at I! a pair of upright supporting structures attachedto the track frames at either side thereof, and at It a pair ofhydraulic jacks mounted on the supports, l5 and by means of which jacksone or the other, or both, of the push members may be lifted.

I have indicated generally at I1 9. multiple hydraulic pump preferablydriven by the power take off of the tractor and at la a valve assemblyconveniently located in the cab by means of which the operator maydivert the oil or other fluid under pressure to the different jacks ashe desires to manipulate his machine.

Referring to Figs. 2 and 3 I have shown the multiple pump I! as a pumpof the gear type driven from a common shaft l9 having three separateoutlets under different conditions. Two outlets may be adequate or agreater number may be required. The three pumps X, Y, and Z draw oil orother fluid under pressure from .a common reserve tank (not shown),through the common intake 20. Each pump is provided with a separatesafety valve M, N, and 0 which in case of overload release the oil backto the common reserve tank from which the three pumps are fed. Valves Aand B are designed to separate or combine the flow from the three pumpsX, Y, and Z. Valves C and D and E govern the separate outlets so thatwhen valves A and B are opened and the three pumps are working with acommon outlet, these valves C, D and E can divert the common stream toone, two or three different jacks.

When valves A and B are closed, the output of the pumps go individuallyto their respective cylinders. When only A is closed, the cylinder onthe output of valve C is the only one operating individually. Valve Boperates identically. When both valves A and B are open the output ofthe pumps go to the cylinders in combination. By leaving valves A and Bopen and closing any one or two of C, D or E, the output of the pumpsmay be directed to any one or two cylinders. The valves A, B, C, D, andE may be of any type, as rotary plugged plunger, poppet, needle, or anycombination thereof.

In Fig. 4 I have shown the same system with plunger type pumps such as Pand Q which accomplish the same purpose as the multiple gear pump shownin Figs. 2 and 3 and, governed by 9.

valve assembly of similar principle, may be used with either a common ora divided flow.

When valve A is closed outputs of pumps go individually to theirrespective cylinders. When valve A is open output of the pumps go to thecylinders in combination. By closing valve A or B output of pumps may bedirected to any one cylinder.

In Fig. 5 I have shown a variant of the multiple gear pump wherein thegears are arranged side by side instead of on a common shaft, allprinciples being the same as in the other drawings, the difference beingonly in the mechanics of housing and hanging gears.

Various other arrangements will suggest themselves to those skilled inthe art and all such as come within the purview of my invention asdefined by the appended claims are to be regarded as covered thereby.

What I therefore claim and desire'to secure by Letters Patent is:

1. In material handling equipment, the combination with a propulsionvehicle and a material moving element propelled thereby, of a pair ofhydraulic lifting jacks mounted on the propulsion vehicle andoperatively connected with the material moving element, a multiple unitpump for supplying plural streams of fluid under pressure to said jacks,a single source of power for operating said pump, and control meansdominant upon said pump and manipulatable to maintain predeterminedlifting speeds on both jacks regardless of loads on either jack varyingfrom zero to capacity and also manipulatable to combine all of the fluidstreams and send them to a single jack to cause said jack to operate atmaximum lifting speed.

2. In material handling equipment, the combination with a propulsionvehicle and a material moving element propelled thereby, of a hydrauliclifting jack mounted on the propulsion vehicle at either side thereofand operatively connected with the material moving element, a multipleunit pump for supplying plural streams of fluid under pressure to saidjacks, a single source of power for operating said pump, and a valveassembly dominant upon said pump and manipulatable to combine all of thefluid streams and send them to a single jack to cause said jack tooperate at maximum lifting speed or to divide the streams uniformly andsend the divided streams to both jacks to cause both jacks to operate atequalized lifting speed on occasions when both jacks are differentlyloaded at the same time.

3. The combination of claim 1 wherein all of the pumping units aredriven from a common drive shaft.

4. The combination of claim 1 wherein the pump is a multiple gear pump.

5. The combination of claim 1 wherein the pump is a multiple plungerpump.

6. The combination of claim 1 wherein a pair of multiple stream pumpsare placed in juxtaplosifttion to each other and driven from a common sa 7. In material handling equipment, the combination with a tractor, amaterial moving element propelled thereby, and push members pivoted attheir rear ends at or near the rear drive sprocket of the tractor andfastened at their forward ends to said material moving element, ofseparate supports mounted on the track frames of the tractor at eachside thereof, separate hydraulic jacks carried by said supports andoperatively connected with said push members, a multiple unit pump for75 supplying plural streams of fluid under pressure to said jacks anddriven from the power take-oil. of the tractor, and a valve assemblylocated within convenient reach of the operator of the tractor anddominant upon saidpump and manipulatable either to combine all of thefluid streams and send them to a single jack to cause said jack tooperate at maximum lifting speed, or to divide the fluid streamsuniformly and send the divided streams both jacks to cause both jacks tooperate at equalized lifting speed on occasions when both jacks aredifferently loaded at the same time.

8. In material handling equipment, the combination with a propulsionvehicle and a material moving element propelled thereby, of a separatehydraulic lifting jack mounted at each side of the propulsion vehicleand operatively connected with the material moving element, a multipleunit pump mounted on the propulsion vehicle, a single source of powerfor driving said pump, said pumping units having a common intake andalso having separate outlets under diiferent conditions, and a valveassembly mounted on the propulsion Vehicle and controlling the supply offluid from said pump to said jacks and including a pair of valvesadapted either to separate or combine the flow of fluid from the severalpumping units to said jacks, and a plurality of other valves separatelygoverning the separate outlets of the several pumping units andeifective when said pair of valves is open and the several pumping unitsare operating with a common outlet to divert the common stream to one orboth of the Jacks.

of claim 8 wherein sepaprovided for all of said 9. The combination ratesafety valves are pumping units.

10. In material handling equipment, the combination with a propulsionvehicle and a material moving element propelled thereby, of a separatehydraulic lifting jack mounted on each side of the propulsion vehicleand operatively connected with the material moving element, a multipleunit pump mounted on the propulsion vehicle, a single source of powerfor driving said pump, said pumping units having a common intake andalso having separate outlets under different conditions, and a valveassembly controlling the supply of fluid from said pump to said jacksand manipulatable either to separate or combine the flow of fluid fromthe several pumping units to said jacks.

11. In material handling equipment, the combination with a propulsionvehicle and a material moving element propelled thereby, of a pair ofseparate lifting members mounted on the propulsion vehicle andoperatively connected with the material moving element, a prime moverfor said lifting members, a single source of power for driving saidprime mover, and control means dominant upon said prime mover forcausing a single jack to operate at maximum lifting speed or for causingboth jacks to operate at equalized lifting speed on occasions when bothjacks are difierently loaded at the same time.

CABLE D. HENRY.

